Insulating mounting for anode grids



4- J. T. MATHEWS 1,943,242

INSULATING MOUNTING FOR ANODE GRIDS Filed May 6, 1931 WNW/5555, INVENTOR 5;- Q J0/7f) TMa/hews.

y. mom BY AT'TORNEY Patented Jan. 9, 1934 UNITED STATES INSULATING MOUNTING FOR ANODE GRIDS John T. Mathews, Wilkinsburg, Pa., assignor to Westinghouse Electric & Manufacturing Company, a corporation of Pennsylvania Application May 6, 1931. Serial No. 535,409

3 Claims.

My invention relates to insulating mountings for anode grids of vapor-electric devices.

It is customary to provide vapor-electric devices, such as mercury-arc rectifiers, with shields about their anodes and also to provide grids in the paths of the arcs. For purpose of convenience the grid is placed in the shield and supported therein by suitable means, usually by bolting to the shield.

Prior to my invention, considerable diiliculty had been experienced in maintaining insulating mountings between shields and grids.

This difliculty arises because of the fact that, when in operation, a quantity of material is lost 15 or sputtered from the anode head of a vaporelectric device. This material, in the form of fine particles, travels up and down the anode shield in the arc path and is deposited on any surface it may strike.

The grids and the supports therefore, being in the direct path of the arc, are eventually coated with the deposited material. When insulating mountings are employed, the deposited material forms a conducting layer thereon, which destroys the benefit of the insulator.

I have found that the sputtered material moves in substantially straight or stream-line paths. Also, I have found that deposition of the sputtered material on any particular surface of the 30 shield, may be prevented by interposing a protecting shield to receive the deposited material.

It is an object of my invention to provide an insulating support for an anode grid having a shield to prevent deposition of conducting material upon a portion of the insulator surface.

It is a further object of my invention to provide a supporting insulator for vapor-electric devices.

Other objects and advantages of my invention will be apparent from the following detailed description, taken in conjunction with the accompanying drawing, in which I Figure 1 is a sectional elevation of an anode and an anode shield embodying my invention, and

Fig. 2 is a, sectional view of a portion of a modification having an additional shielding element.

The apparatus disclosed in the drawing comprises an anode stem 1, an active head 2 and a 0 suitable insulator 3 from which is suspended a substantially cylindrical shield 4, preferably of sheet material. Adjacent to the anode head 2 is an anode grid 5, preferably of conducting material, which is attached to the shield by a plurality of rod-like supports, such as the bolts 6.

The bolts 6 extend through openings 8 in the shield 4 and are insulated therefrom by tubular insulators 10 the internal diameters of which are greater than the diameters of the bolts, so that, when the bolts are properly centered in the insulators by suitable means, such as tubular plugs 12, or, as shown in Fig. 2, by reduced internal diameters, as indicated at 13, the inner portions 15 of the insulators will constitute shields of such lengths that the sputtered material will not be deposited far enough inside them to bridge the surface between the bolts and the shield 4.

This arrangement prevents the sputtered material from being deposited at the junctionbetween the bolt 6 and the insulator, and efiectively prevents bridging from the grid-supporting structure to the anode shields.

In the modification shown in Fig. 2, an additional screen 20, preferably of tubular form, is so placed on the grid as to surround the end portion of the insulator 10 and thus provide a labyrinth-like path to decrease the possibility of sputtered material reaching the interior of the insulator.

While I have shown a specific embodiment of my invention, it is apparent that modifications may be made therein without departing from the spirit and scope of my invention, and I desire, therefore, that only such limitations shall be imposed as are embodied in the accompanying claims or necessitated by the prior art.

I claim as my invention:

1. An insulating support for an anode grid comprising a tubular shield surrounding an anode, a grid within said shield, grid-supporting members interposed between the grid and the shield and embodying tubular insulators, said insulators projecting inwardly and being circumferentially spaced from the cooperating elements of the supporting members, and tubular screens surrounding and spaced from the inner portions of said insulators.

2. An insulating mounting for mounting an anode grid in an anode shield comprising supporting bolts, the shield having side openings to receive said bolts, insulators in said openings having tubular portions extending toward the grid, the inner diameters of said tubular portions being greater than the diameters of said bolts, means for centering the bolts in said insulators, and a screen extending from said grid over said tubular portion.

3. A protective device for an anode comprising a substantially cylindrical shield around the anode, a grid in said shield and spaced from the anode and the shield, supporting means for attaching the grid to the shield comprising insulators, portions of which are spaced from the other elements of said supporting means, and tubular screens attached to said grid and spaced from said insulators for preventing deposition of conducting material on portions of said insulators.

JOHN T. MATHEWS. 

